Preheat oven to 400°F. Line 2 baking sheets with parchment paper. Set aside.: The kitchen instantly warms with a toasty scent when the oven heats, and the parchment gives a smooth, nonstick surface that prevents caramel from gluing to the pan. You want the oven fully heated so cookies bake evenly, forming crisp edges while the centers remain soft. A common misstep is skipping parchment, which can lead to sticky messes if any caramel escapes. Check that racks are centered to allow even circulation of heat.
In the bowl of a stand mixer fitted with the paddle attachment, cream the butter, brown sugar, and granulated sugar until light and fluffy, about 3-5 minutes.: As you cream, the mixture should lighten in color and feel aerated, with a soft, pillowy texture that indicates air has been incorporated for lift. The sound is a gentle whir, and the smell becomes sweet and buttery. Not creaming long enough yields a dense cookie, while overcreaming can make batter too soft. Stop once the mixture looks pale and slightly fluffy.
Add in the eggs, egg yolks, and vanilla extract and mix until incorporated.: The batter will become silkier, glossy, and slightly looser as the eggs emulsify fats and sugars. You should see no streaks of egg white, and the aroma of vanilla will blossom. Adding cold eggs can cause the butter to seize and create lumps, so ensure ingredients are room temperature. Scrape the bowl so everything blends uniformly.
In a separate bowl, whisk the flour, cake flour, cornstarch, baking powder, baking soda, and salt together. Add the flour mixture to the wet ingredients, little by little, beating lightly after each addition.: The dry mix should look evenly combined and pale. When incorporated gradually, the dough comes together without overworking gluten, preserving tenderness. The dough will feel slightly tacky but manageable; if you dump all the flour at once, you risk ending up with a tough, dry cookie. Stop mixing as soon as you cannot see streaks of flour.
Add the chocolate chips and mix until just combined.: As the chocolate chips tumble into the dough, you will see little pockets of dark or milk chocolate dotting the surface. Mix gently so chips remain intact and the dough maintains a soft texture. Overmixing will crush chips and knead the gluten, changing the mouthfeel. Fold until distribution is even.
Use a cookie scoop to gather a portion of the dough in your hand. You should have enough dough for 18 large cookies.: Scooping creates uniform portions so each cookie bakes at the same rate. The dough should be slightly sticky but hold together when scooped. If portions vary, some cookies will bake faster and end up overdone. Keep your scoop consistent and work quickly so the dough does not warm excessively in your hands.
Make an indentation in the ball of dough. Take a caramel and place it in the well of the cookie dough. Pinch the dough to cover the caramel. Gently roll the dough between your hands to form a ball that completely covers the caramel. Place back on the baking sheet, leaving at least 2 inches between the cookies. Repeat until the cookie dough is gone.: Sealing the caramel fully is critical so it melts inward rather than leaking. When sealed well, the exterior looks smooth and you will not see any caramel seams. Pressing too hard can flatten the dough and reduce rise, while failing to seal results in caramel oozing and sticky sheets. Make sure seams are pinched tight and the ball feels taut.
Place the cookie dough balls in the refrigerator to chill for 10 minutes.: Chilling firms the dough and prevents excessive spread, so the cookies bake with a nice dome and soft center. You will notice the dough becomes cooler and less tacky to the touch. Skipping this can create thin, flat cookies where the caramel risks leaking. If chilling longer, allow a minute on the counter before baking so they slice onto the sheet easily.
Bake for 10-12 minutes, or until the edges are set and the middles are still soft. Remove them from the oven and press a few more chocolate chips onto the top of each cookie. Cool on a wire rack for 5-10 minutes and enjoy!: During baking you will hear a faint crackle and smell butter, sugar, and chocolate melding. The edges should look gently golden while the center remains slightly underbaked and jiggly, which yields a tender bite after cooling. A common error is overbaking until the center is firm, losing that gooey texture. Pressing extra chips after baking gives an attractive finish and a melty top when warm. Let cookies rest so the caramel sets just enough to enjoy without burning.